Vodafone is to cut its data-roaming rates for much of Europe in a bid to boost smartphone sales, the operator announced on Monday.

The telco — which used to have a £5-a-day promotion for 25MB of data usage while roaming in other European countries, but dropped that tariff eight months ago in favour of a straight £1-per-megabyte regime — will from 1 December provide an opt-in scheme charging £2 a day for the 25MB. This Vodafone Data Traveller bolt-on, available to both business and consumer customers, covers roaming on competitors' networks as well as on Vodafone's own network, a spokesman for the operator told ZDNet UK.

In addition, Vodafone said that customers on monthly contracts will be able to get 25MB of usage per day for free if they already pay £40 or more per month. If their subscription carries a lower monthly fee, they will be able to pay £10 a month for the same privilege.

Those who do not sign up for Vodafone Data Traveller will continue to pay the company's standard European data-roaming rate of £1 per megabyte up to 5MB, then £5 per 5MB after that.

"This is the year of the smartphone, and we want our 35 million European data users to feel free to use their devices in Europe in the same way as they do at home," Vodafone chief executive Vittorio Colao said in a statement. "We expect smartphone sales in Europe to grow from 32 per cent today to more than 70 per cent by 2013, and we want to drive that growth with [the new] roaming data packages."

The countries where £2 a day or £10 a month will provide 25MB of daily roaming data are: Austria, Belgium, France, Switzerland, the Czech Republic, Germany, Greece, Hungary, Ireland, Italy, Malta, the Netherlands, Portugal, Romania and Spain. Customers roaming in other European countries, such as Luxembourg, will only get 5MB of data usage for the same amount of money.

Vodafone's new roaming rates are also not being consistently applied across the operator group's various European operations: its customers in Italy and Ireland will be able to get 50MB of data usage for a €2 (£1.69) daily fee. The same fee brings only 25MB in all other countries and, in the UK, it is a fee of £2 not €2.

"Each [national Vodafone] operation will look at it on a market-by-market basis," the operator's spokesman told ZDNet UK. "We do keep it under review."

He denied that the move had anything to do with EU digital agenda commissioner Neelie Kroes's warning, made in September, that operators had to allow "the gap between roaming and domestic prices to approach zero" as "significant differences between roaming charges and national tariffs cannot be justified in a true single market". Kroes hinted that, if this did not happen, she would only retain an open mind for a "while longer" as to the nature of her next regulatory steps.

Five years ago, Vodafone was charging £10 per megabyte for data roaming. Asked how Vodafone is now able to bring its charges down to 8p per megabyte on the Data Traveller plan — unless the original roaming charges had not been excessive — the spokesman maintained that "there are costs involved in terminating a call on another network".

"You can bring those costs down — new switching technology does help, traffic preference systems do help," he said, explaining that traffic preference systems allow the operator to "direct the traffic over preferred routes".

Vodafone's new rates do make it the most cost-effective of all UK networks when it comes to European data roaming. T-Mobile's closest package is a Euro Internet Booster that provides 20MB of weekly data usage for £5. Orange has a monthly Europe travel data bundle of 4MB for £5, while 3 charges a straight £1.25 per megabyte and O2 still charges £3 per megabyte.